Lapping machine



June 2Q, 1944. F. J. KENT 2,352,105

LAPPING MACHINE Filed Jan. 28, 1943 2 Sheets-Sheet l l' l I 19 il. 1s

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June 2), i944.

F. J. KENT 2,352,105 LAPPING MACHINE Filed Jan. 28, 1943 2 sheets-sheet 2 6 IN VEN TOR, "feterzh Q/ I lilik/t,

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Patented June 20, 1944 UNlfiisl);V STATES PATENT OFFICE@ 5 2,352,165f-iif.V f

LAPPNGMAC'HINE Frederick'J. Kent, GleniRock, N.- J., assignor to Sipp-Eastwood Corporation, Paterson, N. J.; a.-

e :corporation of New. Jersey applieation Januaryizs, 1943,1 seria1 ria/473,822 r 4 Claims.l (Gli51-f118) the art of lapping, as the abrading of a broad face'of aquartz crystal piece either to develop said face perfectly`v planiformor reduce the piece to agiven thickness, the piece .is positioned with itsfaceagainst the planiform abrading surface of an abrading implementand yone of them is rotated relatively to the yother around an axis perpendicular to said surface.

,Forthispurpose according to the presentl invention `there aretwo structures, onefof which I term the 'abrading structure`becau's'e it provides said planiform abrading surface and the other` what I term the work=abutted structure, andone is rotative relatively tothe other around a Xed axis penetrating and perpendicular to said surface. Having these two structures, the assemblylthey contribute to,form includes, cut by the, plane of s aid .surface,work abutments spaced apart 'less than they diameter of the work and one of which as a. whole is eccentric of, 4andfurther thanthe other from, said. axis arid projects from and provides a workabutted portion of they/orkabuttedstructure. Thereby,vwith said assembly `alsofincluding 'means to holdthe. Work (assumed tobe` substantially circular and of adiameter somewhat greater than that of thespacing of said abutments) in contact with andwith its own axis perpendicular to said .surface and in an orbit concentricwith.saidstructures and extending be- 'tweenthe abutments, .the work will in a novel .way be confined, during the abrading, 'against displacement yrelatively to the work-abutted vst'ructure'by'resistance applied, i. e.,.by the abut- .ments, to -its periphery. .Preferably theabrading vstr ucture is rotative and the. other structure fixed whereby the work `will during abradingbe in a constant position. v

If, during the abrading, at least one v of the abutmentsis rotated around its own axis it may by. tractive effort applied to the periphery of the Work rotate the latter around its ownaxis, thereby uniformly tol disperse the abrasion; if both are rotatedasin the same direction, the tractive 'effortwill increased to insure rotation of 'the e i as work e. Y Ihe abrading structure may have the part thereof having the abrading surface in the form of'acirculardiskwhoseaxis is the axis of relative rotationv of said structures, `in which case the abutment lflrsteabove mentioned is eccentric of the disk. y Thereby access to the work for rotating it is ,had even thoughthe means to holdthe work ,in contact with the abrading surface takes the ...form o fadisk of approximately the same diamener as 'that ofthe' abrading structure-*t0 wir, so

that each disk may limit the flexion of the Work toward such disk in the case where the work is quite flexible. y

I n the example said means to hold thework in contact with said surface itself provides an abrading surface, being incidentally confined against rotative displacement'relatively to the abrading structure. This, howevenis immaterial to the invention as above broadly outlined'. f And it lis also immaterial how relative rotation as between the vtwo aforesaid structures is effected, i. e., whether or not by the saine means which rotates oneor bothof the abutments.

In additiontothe foregoing the invention provides for relief ofthepressure to Which the work is subjected by theabrading structureland the means for holding the Work in contact with the abrading surface in the event one or the other oi these acts to dog the Work.v

In the drawings, Fig. 1 is a side elevation of an apparatus .or machine embodying .the invention; l

Fig. 2 a planthereof; f i r Fig. 3 a plan .of the abrading side of,`sa'y',' the lower lap;

Fig. 3a is a fragmentary sectional view of a lap;

y Figs. `4 and 4a are, respectively, a plan and a side elevationV of what is here-taken as 4the work,

machine, as seen from the right in Fig. gl; and

Fig.9 is aside elevation of a portion ofthe 4main. shaft;

A l frame or lsupporting structure is formed by a. base .|st andards 2 and atable'3 rigidly held together by screws 4. On the base arean electric motor 5 and aswitch 6 for controlling the motor. A main shaft 'l is stepped in a socket la in thebase on a ballfbearing 8 and has a bearing inthe table, being confined by thebase and table toa fixed axisof rotation therein. By a worm on themotor shaft and a worrn,wheel I i) on the main. shaft, intergeared witheach other, such shaft is driven by the motonV *Alower disk or lap I I Ahas an integral depending. half-hub! I awhich coacts with another halfhub 'IZ-Whenthe two half-hubs are secured togeth'er by screws i3, to clamp the lower lap rigidly to the mairlshaft, said shaft being perpendicular to theV upper or abrading side of the lap, or at least to its actual abrading surface, and central thereof.

I4 is the upper lap having an elongated upstanding hub Ha which at each of its upper and lower ends, as at l5, obtains a limited bearing on the shaft, the'lower side of lap I2, or at least its actual abrading surface, being thus confined to parallelism with the actual lapping surface at the lower sidev of the1lower, lap as wellas concentric and coincident therewith.

The actual lapping surface (by which I mean a planiform surface) of each lap is a relief surface (or one that adjoins at each long side thereof a surface extending relatively back fromit) such as is shown at I6 in Figs. 3 and 31.16. the two such relief surfaces are here, continuous; and-of the same width and diameter. i

The work proper a, which ishere assumed to be a quartz crystal oscillator or resonator `of quite little thickness, as but a small fraction of an inch' thick, is to be received in a work-holder l1 so that its broad face or its opposite broad faces to be abraded may undergo abrading independently of the work-holder, which is therefore of thinner but stiff material here in the form of a circular disk having a central aperturellu. of such-conformation, as rectangular, that when'the work is received therein complete rotation of'either of the parts of the assembly, or work they form relatively to the other is prevented.

For entering the work between the laps the upper lap may be elevated, to be supported temporarily in elevated state by a hook |8, pivoted to a collar I9 fixed on said shaft, and to be engaged with a radial stud on the hub Ida.

When the main shaft and', withv it, the lower lap is driven a depending pin 2| yfastto said collar engages said stud to drive the upperlap syn'- chrony with the lower lap. f

The work, while the laps undergo rotation, is

to be rotated around an axis penetrating `and preferably central of the work and its advance with the laps opposed. For this purpose there is journaled in a pedestal 22 'opstanding from the table a rotary member comprising a spindle 23 parallel with the main shaft, and atraction roller 24 fast to the spindle and supported on the pedestal; a gear 25 is vfixed to the spindle below the table and geared through a gear' 25:r with 'a gear 26 fast to the main shaft. In effect one with* the shaft is preferably an axial or traction portion,

as a sleeve 2l, both it and the roller being cut by a plane between and parallel with the actual abrading or lapping surfaces of the two laps when they are in lapping relation to ,the work.v The work isA (here) of a diameter greater than the space between the traction elements 24-2'|. The roller, sleeve, and actual lapping surface aofeach lap should all be so proportioned that when vthe work abuts said roller and sleeve the axis of rotation of the work will penetrate said actuallapping surfaces and also be in an :orbit coaxial with the laps and extending between the roller and sleeve. When the machine is operating to lap the work, assumed to have been interposed between and subjected to compression bythe laps incident to (here) the weight of the upper (or yielding) lap, the laps tend to advance the work around the main shaft, but this is opposed by the traction elements, and meanwhile the work is made by the gearing 25-.2531-25 to undergo rotation around an axis penetrating it. The work being ,thus opposed `it is not indispensable whether either or both of said traction'elem'ents actually impel said assembly, but to insure constant impelling, with consequently a uniform dispersion of the lapping action on the work, it is preferable that both be rotated. l

Instead of abrasive action being made to affect the work it may be caused, as in reconditioning one or both lapping surfaces, to affect one or both of the latter. Thus in Figs. 6 and 7 is shown a circular disk 28 of the samediameter as disk Il and having a circular central flatraised abrading portion 28a at each face thereof and of a diameter at least not less than the width of the relief surface of either lap.

In Figs. 1 and 8 the pin 2| has its lower end portion bent off to `provide a cam surface 2|a engaged by a stud 20 and arranged to cam the upper lap-including member Ill-Ma from the other such member, formed by the main shaft and lower lap, in the event that the work and one of the laps dog each other in such a way that, in the absence of the camming to induce lifting of the upper or yielding lapping member, injury to the work or the lapping surface would occur.

In some instances the work-holder, besides having a central aperture vfor a single piece, may have supplemental apertures. Thus in Fig. 5 29 is the work-holder having, besides the central aperture 29a, other apertures 29h arranged around the centralV aperture.

The part shown at 3 0 is a receptacle for a mixture of water and comminuted abrasive material.

In the example, the aforementioned abrading structure is afforded by the lap Il; the workabutted structure by the frame' formed by parts |-2-3 and 22 the abutments by the member 23-24 and sleeve 21; and the means to hold the work in contact with the abrading surface of the abrading structure by the upper lap. Thefmeans to rotate the abutments is afforded by the train of gears and shaft '1.` Parts 210 and 2| are termed contacts inthe appended claims.'

It will be apparent to anyone skilled in the art of lapping an article such as a quartzcrystal oscillator or resonator, so that in the finished article the abrading of each face thereof as treated will be perfectly parallel with the face thereof as it comes to the'treatment, that the lapping s urfaces of the two laps should be definitely'confined to parallelism. Hence,` whatever may be the maximum diameter of the area of so much of said surfaces as are directly opposite to each other, the bearings l5 are spaced apart according to my invention a distance not substantiallyless than such diameter and they confine the lapping members with their common axis in vconstant perpendicular relation to said surfaces.

Having thus fully described my invention, what I claim is:

1. An assembly for lapping the herein-defined work, said assembly including an abrading structure and a work-.abutted structure one of which is rotative relatively to the other arounda fixed axis, the .abrading str ucture providinga planiform abrading surface perpendicular to andl extending around said axis and said assembly also including, cut by the plane of said surface, work abutments spaced apart lessthan the diameter of the work and one of, which is as awholeeccentrcof, and further than the other `abutment from, said axis andprojects from and provides a work-abutted portiongof the work-abutted structure, in combination with means to hold the work in contact withn said .surface when positioned thereagainst and with its own axis substantially perpendicular to said surface and in an orbit coaxial with said structures and extending between said abutments. v

2. An assembly for lapping the herein-defined work, said assembly including an abrading structure and a work-abutted structure one of which is rotative relatively to the other around a fixed axis, the abrading structure providing a planiiorm abrading surface perpendicular to and extending around said axis and said assembly also including, cut by the plane of said surface, work abutments spaced apart less than the diameter of the work and one of which is substantially circular and rotative around an axis penetrating it substantially centrally and perpendicular to said surface and one of which abutments is as a whole eccentric of, and further than the other abutment from, the rst-named axis and projects from and provides a work-abutted portion ofthe work-abutted structure, in combination with means to hold the work in contact with said surface when positioned thereagainst and with its own axis substantially perpendicular to said surface and in an orbit coaxial with said structures and extending between said abutments, `and means to rotate the rotative abutment around` Y its own axis.

3. An assembly for lapping the herein-defined work, said assembly including an abrading structure and a work-abutted structure one of which is rotative relatively to the other around a fixed axis, the abrading structure providing a planiform abrading surface perpendicular to and extending around said axis and said assembly also including, cut by the plane of said surface, work abutments spaced apart less than the diameter the other of which abutments is also circular and penetrated centrally thereof by and rotative I around therst-named axis, in combination with means to hold the Workin contact with said surface when positioned thereagainst and with its own axis substantially perpendicular to said surface and in .an orbit coaxial with said structures and extending between said abutments, and means to rotate both abutments around their respective own axes inthe same rotative direction. ,y 4. The assembly` set forth in claim 1 characterized by the part of the abrading structure having said surface consisting of a; substantially circular disk whose axis is the first-named axis and by the first-named abutment being eccentric of the disk.

FREDERICK l KENT: 

